The present invention relates to the selective hydrogenation of unsaturated hydrocarbon polymers. More specifically, the present invention relates to the use of specific catalytic compounds to hydrolyze pendant or external points of unsaturation on hydrocarbon polymers made from polyunsaturated monomers such as dienes and trienes.
Heretofore, various catalysts such as triphenylphosphine complexes of rhodium, ruthenium, and iridium have been prepared, see Journal of the Chemical Society [A] 1968 Page 2665-2670 and 3143-3150; Journal of the Chemical Society [A] 1969, Page 2610-2615. Generally, the various triphenylphospine compounds have been shown to be efficient catalysts including the homogeneous hydrogenation of 1-alkenes.
According to the present invention, it has been found that when certain complexes of rhodium, ruthenium and iridium are utilized in the hydrogenation of unsaturated polymers, that the hydrogenation is unexpectedly selective in contrast to various conventional nickel and cobalt complex hydrogenation catalysts which show very little, if any, selectivity.